Experimental study of contact angle and surface energy of a single aramid fibre and its relation on frictional behaviour of fibre-fibre contact

Surface energy has a significant impact on the adhesion and friction behaviour of fibres in composite materials. Finding the surface energy of a single fibre, on the other hand, maybe challenging. In this work, the surface energy of single aramid fibre is calculated using dynamic contact angle measurements. The contact angles of three different types of Twaron® aramid fibres with varying treated materials and thicknesses are tested in a series of test liquids. As a result of the changing surface characteristics of the fibre, the surface energy of treated fibre is found to be approximately 37% greater than that of untreated fibre. The thickness of the fibre also affects its surface energy because thicker fibres have a larger contact area, which increases surface energy in the region of contact. At specific applied normal load conditions, it can be found that the coefficient of friction increased as the total surface energy in the area of the contact interface increased.</p

Case study of the effectiveness of passive grease trap for management on domestic kitchen waste water

Household waste, generally known as trash or garbage is mostly includes food wastes, product packaging, and other miscellaneous inorganic wastes that are coming from domestic household. Grease waste such as oil and fats can contaminate water and also clot on pipes provoking blockages. Thus, waste water from kitchen sink need a proper way of filtration. Grease trap developed in this paper is viable in trapping the grease residue. The experiments have been conducted in controlled environment and the objectives are to investigate the effectiveness of grease trap by proving the existence of retention time and the expected ratio of collected water and oil during experiment process using a prototype model

Modelling investigation on fiber-on-fiber contacts for synthetic fibers

Fiber is the main load bearer for engineering structures such as composites and rope. With characteristics such as superior mechanical strength, lightweight and flexible, synthetic fibers have replaced metals in many engineering applications. Due to its cylindrical body, contact between adjacent fibers can be subjected to various contact conditions, depending on the skew angle between the fibers. Fibers have large surface area-to-volume ratio, hence fiber contacts can be influenced by the surface forces such as adhesion. Adhesion in fiber contacts is governed by various factors such as surface roughness, intermolecular distance and the environment. There are various contact models available that can describe adhesive contacts. However, none of these models can describe adhesive elliptical contacts that are influenced by the angle between the contacting bodies and occur between materials that are neither rigid nor highly elastic. Hence, the development of an adhesive contact model for elliptical contacts is essential. In this thesis, the adhesive contact mechanics between fibers are investigated in the following aspects: 1. A contact model to describe the elliptical contact between cylindrical bodies with adhesion has been developed, for a range of skew angles. Realistic geometry assumptions on the load-dependent adhesive region have also been developed numerically. 2. An adhesion map for elliptical contacts has been constructed to guide the selection of suitable contact models. The construction is based on the aforementioned adhesive contact model. 3. The presence of adhesion has been shown to be significant in the contact between fibers in hierarchical structures

Extending the Double-Hertz Model to Allow Modeling of an Adhesive Elliptical Contract

An adhesive elliptical contact is normally found in microscale applications that involve cylindrical solids, crossing at an angle between 0° and 90°. Currently, only one model is available to describe the elliptical contact’s surface interaction: the approximate Johnson–Kendall–Roberts (JKR) model which is limited to soft materials. In this paper, a new adhesive elliptical model is developed for a wide range of adhesive contacts by extending the double-Hertz theory, where adhesion is modeled by the difference between two Hertzian pressure distributions. Both Hertzian pressures are assumed to have an equivalent shape of contact areas, the only difference being in size. Assuming that the annular adhesive region is obtained by the area difference between the two Hertzian contact areas, the pull-off force curves can be calculated. In the limiting case of an adhesive circular contact, the results are very close to results from the existing models. However, for an adhesive elliptical contact in the JKR domain, lower pull-off forces are predicted when compared to the JKR values. Unlike the developed model, the shape of the JKR contact area varies throughout contact. Results show, particularly for conditions close to the JKR domain, that it is important to take into account that the adhesive region is the result of the two Hertzian contact areas having a non-equivalent shap

Friction between single aramid fibres under pre-tension load

Understanding the friction mechanism at microscale of fibrous material is important as it is one of the key roles in governing the behaviour of fibre assemblies at meso and macroscale. However, mechanical stress such as tension may also influence the frictional behaviour. In this study the frictional behaviour between fibres under pre-tension is explored. A new experimental setup was successfully developed to measure the friction force between two single aramid fibres at perpendicular contact. Although pre-tension influences the bending stiffness of the fibre, the results show that the effect of pre-tension on the contact length is relatively small. The elastic deformation of the contact dominates over the ‘wrapping effect’, generating the contact area over which the interfacial shear takes place

Microstructural properties and surface roughness of 3D printed open cell-foam

In this study, the microstructure of open-cell metal foam was generated and reconstructed, to produce a new generation of open-cell foam, which is called 3D printed open-cell foam. At the current stage of research, nylon powder and plastic acid are utilized as the materials for two different 3D printing technologies: Selective Laser Sintering (SLS) and Fused Deposition Modelling (FDM), respectively. The microstructural properties and surface roughness of the 3D printed open-cell foam are investigated using CAD files and microscope images. The surface smoothness and structure strength are found to be dependent on the printing technologies, material employed, and foam size. However, the SLS technology produced smoother ligament surfaces with fewer residues than using the FDM. The ligaments of the small-size 3D printed open-cell foam at the exact size of the metallic foam, on the other hand, are weak and easily shattered. This study also found that the trends of pressure drop from additive manufacturing methods agreed to the original metallic open-cell foam, which are decreasing with the increase of pore sizes.</p

Microstructural properties and surface roughness of 3D printed open cell-foam

In this study, the microstructure of open-cell metal foam was generated and reconstructed, to produce a new generation of open-cell foam, which is called 3D printed open-cell foam. At the current stage of research, nylon powder and plastic acid are utilized as the materials for two different 3D printing technologies: Selective Laser Sintering (SLS) and Fused Deposition Modelling (FDM), respectively. The microstructural properties and surface roughness of the 3D printed open-cell foam are investigated using CAD files and microscope images. The surface smoothness and structure strength are found to be dependent on the printing technologies, material employed, and foam size. However, the SLS technology produced smoother ligament surfaces with fewer residues than using the FDM. The ligaments of the small-size 3D printed open-cell foam at the exact size of the metallic foam, on the other hand, are weak and easily shattered. This study also found that the trends of pressure drop from additive manufacturing methods agreed to the original metallic open-cell foam, which are decreasing with the increase of pore sizes.Process and Energ